Commit | Line | Data |
---|---|---|
457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
41d73ec0 PM |
2 | #include <linux/types.h> |
3 | #include <linux/netfilter.h> | |
4 | #include <net/tcp.h> | |
5 | ||
6 | #include <net/netfilter/nf_conntrack.h> | |
7 | #include <net/netfilter/nf_conntrack_extend.h> | |
8 | #include <net/netfilter/nf_conntrack_seqadj.h> | |
9 | ||
48b1de4c PM |
10 | int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
11 | s32 off) | |
12 | { | |
13 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
14 | struct nf_conn_seqadj *seqadj; | |
15 | struct nf_ct_seqadj *this_way; | |
16 | ||
17 | if (off == 0) | |
18 | return 0; | |
19 | ||
20 | set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); | |
21 | ||
22 | seqadj = nfct_seqadj(ct); | |
23 | this_way = &seqadj->seq[dir]; | |
24 | this_way->offset_before = off; | |
25 | this_way->offset_after = off; | |
26 | return 0; | |
27 | } | |
28 | EXPORT_SYMBOL_GPL(nf_ct_seqadj_init); | |
29 | ||
41d73ec0 PM |
30 | int nf_ct_seqadj_set(struct nf_conn *ct, enum ip_conntrack_info ctinfo, |
31 | __be32 seq, s32 off) | |
32 | { | |
33 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
34 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
35 | struct nf_ct_seqadj *this_way; | |
36 | ||
37 | if (off == 0) | |
38 | return 0; | |
39 | ||
db12cf27 | 40 | if (unlikely(!seqadj)) { |
f2661adc | 41 | WARN_ONCE(1, "Missing nfct_seqadj_ext_add() setup call\n"); |
db12cf27 JDB |
42 | return 0; |
43 | } | |
44 | ||
41d73ec0 PM |
45 | set_bit(IPS_SEQ_ADJUST_BIT, &ct->status); |
46 | ||
47 | spin_lock_bh(&ct->lock); | |
48 | this_way = &seqadj->seq[dir]; | |
49 | if (this_way->offset_before == this_way->offset_after || | |
23dfe136 PO |
50 | before(this_way->correction_pos, ntohl(seq))) { |
51 | this_way->correction_pos = ntohl(seq); | |
41d73ec0 PM |
52 | this_way->offset_before = this_way->offset_after; |
53 | this_way->offset_after += off; | |
54 | } | |
55 | spin_unlock_bh(&ct->lock); | |
56 | return 0; | |
57 | } | |
58 | EXPORT_SYMBOL_GPL(nf_ct_seqadj_set); | |
59 | ||
60 | void nf_ct_tcp_seqadj_set(struct sk_buff *skb, | |
61 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
62 | s32 off) | |
63 | { | |
64 | const struct tcphdr *th; | |
65 | ||
66 | if (nf_ct_protonum(ct) != IPPROTO_TCP) | |
67 | return; | |
68 | ||
69 | th = (struct tcphdr *)(skb_network_header(skb) + ip_hdrlen(skb)); | |
70 | nf_ct_seqadj_set(ct, ctinfo, th->seq, off); | |
71 | } | |
72 | EXPORT_SYMBOL_GPL(nf_ct_tcp_seqadj_set); | |
73 | ||
74 | /* Adjust one found SACK option including checksum correction */ | |
75 | static void nf_ct_sack_block_adjust(struct sk_buff *skb, | |
76 | struct tcphdr *tcph, | |
77 | unsigned int sackoff, | |
78 | unsigned int sackend, | |
79 | struct nf_ct_seqadj *seq) | |
80 | { | |
81 | while (sackoff < sackend) { | |
82 | struct tcp_sack_block_wire *sack; | |
83 | __be32 new_start_seq, new_end_seq; | |
84 | ||
85 | sack = (void *)skb->data + sackoff; | |
86 | if (after(ntohl(sack->start_seq) - seq->offset_before, | |
87 | seq->correction_pos)) | |
88 | new_start_seq = htonl(ntohl(sack->start_seq) - | |
89 | seq->offset_after); | |
90 | else | |
91 | new_start_seq = htonl(ntohl(sack->start_seq) - | |
92 | seq->offset_before); | |
93 | ||
94 | if (after(ntohl(sack->end_seq) - seq->offset_before, | |
95 | seq->correction_pos)) | |
96 | new_end_seq = htonl(ntohl(sack->end_seq) - | |
97 | seq->offset_after); | |
98 | else | |
99 | new_end_seq = htonl(ntohl(sack->end_seq) - | |
100 | seq->offset_before); | |
101 | ||
b44b565c G |
102 | pr_debug("sack_adjust: start_seq: %u->%u, end_seq: %u->%u\n", |
103 | ntohl(sack->start_seq), ntohl(new_start_seq), | |
104 | ntohl(sack->end_seq), ntohl(new_end_seq)); | |
41d73ec0 PM |
105 | |
106 | inet_proto_csum_replace4(&tcph->check, skb, | |
4b048d6d | 107 | sack->start_seq, new_start_seq, false); |
41d73ec0 | 108 | inet_proto_csum_replace4(&tcph->check, skb, |
4b048d6d | 109 | sack->end_seq, new_end_seq, false); |
41d73ec0 PM |
110 | sack->start_seq = new_start_seq; |
111 | sack->end_seq = new_end_seq; | |
112 | sackoff += sizeof(*sack); | |
113 | } | |
114 | } | |
115 | ||
116 | /* TCP SACK sequence number adjustment */ | |
117 | static unsigned int nf_ct_sack_adjust(struct sk_buff *skb, | |
118 | unsigned int protoff, | |
41d73ec0 PM |
119 | struct nf_conn *ct, |
120 | enum ip_conntrack_info ctinfo) | |
121 | { | |
530aad77 | 122 | struct tcphdr *tcph = (void *)skb->data + protoff; |
41d73ec0 | 123 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); |
530aad77 | 124 | unsigned int dir, optoff, optend; |
41d73ec0 PM |
125 | |
126 | optoff = protoff + sizeof(struct tcphdr); | |
127 | optend = protoff + tcph->doff * 4; | |
128 | ||
86f04538 | 129 | if (skb_ensure_writable(skb, optend)) |
41d73ec0 PM |
130 | return 0; |
131 | ||
530aad77 | 132 | tcph = (void *)skb->data + protoff; |
41d73ec0 PM |
133 | dir = CTINFO2DIR(ctinfo); |
134 | ||
135 | while (optoff < optend) { | |
136 | /* Usually: option, length. */ | |
137 | unsigned char *op = skb->data + optoff; | |
138 | ||
139 | switch (op[0]) { | |
140 | case TCPOPT_EOL: | |
141 | return 1; | |
142 | case TCPOPT_NOP: | |
143 | optoff++; | |
144 | continue; | |
145 | default: | |
146 | /* no partial options */ | |
147 | if (optoff + 1 == optend || | |
148 | optoff + op[1] > optend || | |
149 | op[1] < 2) | |
150 | return 0; | |
151 | if (op[0] == TCPOPT_SACK && | |
152 | op[1] >= 2+TCPOLEN_SACK_PERBLOCK && | |
153 | ((op[1] - 2) % TCPOLEN_SACK_PERBLOCK) == 0) | |
154 | nf_ct_sack_block_adjust(skb, tcph, optoff + 2, | |
155 | optoff+op[1], | |
156 | &seqadj->seq[!dir]); | |
157 | optoff += op[1]; | |
158 | } | |
159 | } | |
160 | return 1; | |
161 | } | |
162 | ||
163 | /* TCP sequence number adjustment. Returns 1 on success, 0 on failure */ | |
164 | int nf_ct_seq_adjust(struct sk_buff *skb, | |
165 | struct nf_conn *ct, enum ip_conntrack_info ctinfo, | |
166 | unsigned int protoff) | |
167 | { | |
168 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); | |
169 | struct tcphdr *tcph; | |
170 | __be32 newseq, newack; | |
171 | s32 seqoff, ackoff; | |
172 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
173 | struct nf_ct_seqadj *this_way, *other_way; | |
8d11350f | 174 | int res = 1; |
41d73ec0 PM |
175 | |
176 | this_way = &seqadj->seq[dir]; | |
177 | other_way = &seqadj->seq[!dir]; | |
178 | ||
86f04538 | 179 | if (skb_ensure_writable(skb, protoff + sizeof(*tcph))) |
41d73ec0 PM |
180 | return 0; |
181 | ||
182 | tcph = (void *)skb->data + protoff; | |
183 | spin_lock_bh(&ct->lock); | |
184 | if (after(ntohl(tcph->seq), this_way->correction_pos)) | |
185 | seqoff = this_way->offset_after; | |
186 | else | |
187 | seqoff = this_way->offset_before; | |
188 | ||
8d11350f GF |
189 | newseq = htonl(ntohl(tcph->seq) + seqoff); |
190 | inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false); | |
191 | pr_debug("Adjusting sequence number from %u->%u\n", | |
192 | ntohl(tcph->seq), ntohl(newseq)); | |
193 | tcph->seq = newseq; | |
194 | ||
195 | if (!tcph->ack) | |
196 | goto out; | |
197 | ||
41d73ec0 PM |
198 | if (after(ntohl(tcph->ack_seq) - other_way->offset_before, |
199 | other_way->correction_pos)) | |
200 | ackoff = other_way->offset_after; | |
201 | else | |
202 | ackoff = other_way->offset_before; | |
203 | ||
41d73ec0 | 204 | newack = htonl(ntohl(tcph->ack_seq) - ackoff); |
4b048d6d TH |
205 | inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack, |
206 | false); | |
8d11350f | 207 | pr_debug("Adjusting ack number from %u->%u, ack from %u->%u\n", |
41d73ec0 PM |
208 | ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq), |
209 | ntohl(newack)); | |
41d73ec0 PM |
210 | tcph->ack_seq = newack; |
211 | ||
530aad77 | 212 | res = nf_ct_sack_adjust(skb, protoff, ct, ctinfo); |
8d11350f | 213 | out: |
41d73ec0 PM |
214 | spin_unlock_bh(&ct->lock); |
215 | ||
216 | return res; | |
217 | } | |
218 | EXPORT_SYMBOL_GPL(nf_ct_seq_adjust); | |
219 | ||
220 | s32 nf_ct_seq_offset(const struct nf_conn *ct, | |
221 | enum ip_conntrack_dir dir, | |
222 | u32 seq) | |
223 | { | |
224 | struct nf_conn_seqadj *seqadj = nfct_seqadj(ct); | |
225 | struct nf_ct_seqadj *this_way; | |
226 | ||
227 | if (!seqadj) | |
228 | return 0; | |
229 | ||
230 | this_way = &seqadj->seq[dir]; | |
231 | return after(seq, this_way->correction_pos) ? | |
232 | this_way->offset_after : this_way->offset_before; | |
233 | } | |
234 | EXPORT_SYMBOL_GPL(nf_ct_seq_offset); | |
235 | ||
23f671a1 | 236 | static const struct nf_ct_ext_type nf_ct_seqadj_extend = { |
41d73ec0 PM |
237 | .len = sizeof(struct nf_conn_seqadj), |
238 | .align = __alignof__(struct nf_conn_seqadj), | |
239 | .id = NF_CT_EXT_SEQADJ, | |
240 | }; | |
241 | ||
242 | int nf_conntrack_seqadj_init(void) | |
243 | { | |
244 | return nf_ct_extend_register(&nf_ct_seqadj_extend); | |
245 | } | |
246 | ||
247 | void nf_conntrack_seqadj_fini(void) | |
248 | { | |
249 | nf_ct_extend_unregister(&nf_ct_seqadj_extend); | |
250 | } |